/*
 * Copyright (C) 2011 Nicola Bonzanni
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package nl.vu.few.ibivu.jlemon;

import java.util.NoSuchElementException;

import nl.vu.few.ibivu.jlemon.concepts.ItemIterator;

public abstract class AbstractIterator<E> implements ItemIterator<E> {
	protected E current;
	protected E next;
	
	public AbstractIterator() {
		super();
	}
	
	public AbstractIterator(E current, E next) {
		super();
		this.current = current;
		this.next = next;
	}

	@Override
	public boolean hasNext() {
		return (next != null);
	}
	
	@Override
	public E next() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		current = next;
		next = computeNext();
		return current;
	}

	@Override
	public void remove() {
		throw new UnsupportedOperationException();
	}
	
	public E peek() {
		return current;
	}
	
	protected abstract E computeNext();

}
